Chemical sensors are used in a wide variety of applications involving the measurement of various parameters in chemical environments. These measurements are used both in the laboratory and for on-line process control. For example, chemical sensors may be used to measure pH levels or conductivity of chemicals. Normally, these sensors and the related measurement and data acquisition equipment are proximately located and connected by wiring. Often, however, this equipment is placed in locations that have aggressive chemical environments. As a result, measurement and acquisition of data may be difficult and tends to be inaccurate. In addition, it may be expensive to locate data acquisition equipment at every sensor. Therefore, it is frequently necessary to multiplex acquisition equipment among multiple sensors.
Another source of problems with present chemical sensor systems is the wiring itself. Noise may be introduced into the measurement system due to noise induction in the wiring between the sensors, measurement circuits, and data acquisition equipment. In addition, the use of wiring tends to result in no galvanic separation, which may cause ground loops or isolation problems.
Another problem results when attempting to build chemical measurement systems in which data acquisition equipment is multiplexed between multiple sensors. Such systems require data acquisition equipment to be physically moved between different sensors to effectively multiplex the equipment. This results in an inconvenience to the user of the chemical measurement system. Furthermore, additional problems may occur due to the need to constantly detach and reattach data acquisition equipment to different sensors.